It is known to create NC data (NC program) for operating a combined machining apparatus adapted to perform plural kinds of machining, by the use of automatic programming apparatuses. Since a conventional programming apparatus is a single purpose device having a function of creating NC data for one particular machining alone, plural kinds of programming apparatuses are employed for creating NC data for combined machining.
For example, in the case of creating NC data for combined machining for carrying out turning and milling together, part programs respectively relating to turning and milling are created beforehand. Then, NC data for turning is created based on the part program for turning by the use of a programming apparatus, whereas NC data for milling is created based on the part program for milling by means of another programming apparatus. Further, NC data for turning and milling are so edited as to create NC data for the combined machining.
According to the above conventional method, it requires a great deal of time and labor to create the NC data for combined machining, and an error is likely to occur in an editing operation of NC data such that input sequence of NC data is mistaken.